This application claims the benefit of Korean Application No. 2002-41968, filed Jul. 18, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1 Field of the Invention
The present invention relates generally to magnetrons, and more particularly, to an antenna connecting structure of a magnetron, which allows vanes to have the same frequency characteristics when an antenna combines with at least one of the vanes.
2. Description of the Related Art
As is well known to those skilled in the art, an antenna of a microwave oven""s magnetron serves to radiate high-frequency electromagnetic waves oscillated from an anodic part to a cooking cavity.
FIG. 1 is a sectional view showing a structure to connect an antenna to a vane in a conventional magnetron. As shown in FIG. 1, the magnetron includes an antenna 1 having a thin and long rod-shaped body. The antenna 1 upwardly extends to be connected at its first end to a radiating tube. A second end of the antenna 1 is connected to one of vanes 3 which are radially arranged along an inner surface of a hollow anodic cylinder 2. In order to connect the antenna 1 to the vane 3, an antenna seating recess 4 is formed on an upper edge of the vane 3 at a position corresponding to the antenna 1 so that the antenna 1 is seated in the antenna seating recess 4.
When electrons radiate from a filament 5 to an inside edge of the vane 3, a Lorentz force is applied to the electrons by an electric field and a magnetic field which cross at a right angle, so that the electrons actively rotate in an actuation space 6. Inside edges of the vanes 3 are affected by a high-frequency electric field, so that there occurs a high-frequency oscillation of cavity resonators. When a high-frequency voltage is induced by the high-frequency oscillation, microwaves are generated in the high-frequency electric field and are radiated through the antenna 1 to an outside, thus finally reaching a cooking cavity.
Since the high-frequency oscillation is determined by a resonance frequency of each of the cavity resonators, the resonance frequency is determined by a size of each cavity defined by two neighboring vanes 3 and an inner surface of the anodic cylinder 2.
The vanes 3 are radially arranged on the inner surface of the anodic cylinder 2 in such a way as to face a central axis of the anodic cylinder 2. The cavity resonators are formed by the cavity defined by a pair of the vanes 3 and the inner surface of the anodic cylinder 2. Inductance of the cavity resonator is determined by lengths of two neighboring vanes 3. Capacitance of the cavity resonator is determined by surface areas of facing surfaces of the neighboring vanes 3.
However, when the antenna 1 is connected to the antenna seating recess 4 of the at least one of the vanes 3, there is a difference in area between the vane 3 connected to the antenna 1, and two vanes 3 adjacent to the vane 3 that are connected to the antenna 1. Thus, the conventional magnetron has a problem in that there is a difference in capacitance between the vane 3 connected to the antenna 1 and the two vanes 3 adjacent to the vane 3 connected to the antenna 1. Therefore, different resonance frequencies are generated, thus degrading an operational efficiency of the magnetron.
Accordingly, it is an aspect of the present invention to provide a magnetron, which accomplishes a symmetrical structure of resonators, thus allowing the resonators to have the same frequency characteristics.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other aspects of the present invention are achieved by providing a magnetron including a filament to irradiate thermoelectrons, a plurality of anodic vanes arranged around the filament in radial directions, and an antenna connected to at least one of the anodic vanes. A vane connected to the antenna is provided with an antenna holding part, and the antenna holding part outwardly extends from an edge of the vane by a predetermined length to connect the antenna to the vane.